Increasingly, the 2012 presidential election appears to be dividing along a pair of fault-lines.

The first is demographic: old versus new America.

President Obama’s reelection depends increasingly on a coalition of minorities and younger voters, the same groups that helped put him in office. Their overall numbers are increasing, but the president’s ability to turn them out this year at anywhere close to 2008 levels remains in doubt (at least among Latinos and younger whites; the black vote is virtually certain to be there again for Obama). Their potential explains why Democrats have sought to portray the election as the future against the past.

Mitt Romney, meanwhile, is likely to become president only if he can improve on John McCain’s performance among whites, who represent a declining share of the U.S. population. The GOP candidate’s recent campaign swings have been through areas where whites make up a disproportionate share of the population — including portions of the old Midwest Rust belt and southwest Virginia. A potential key to mobilizing conservative whites: voter drives by Christian organizations to sign up millions of unregistered evangelicals; one of Romney’s biggest advantages over Obama, according to the Gallup Poll, comes from religious whites, who favor the Republican by better than 2-to-1. But Latinos have yet to warm to the GOP candidate, favoring Obama by 2-to-1 in several polls.

The other divide of surpassing importance in this year’s presidential election is geographic: it's the gulf between a relative handful of “battleground” states, which are already getting pounded by campaign commercials, and the rest of the country, where most of America lives and which has largely been spared.

America isn't so much a country as an uneasily balanced melange of two very distinct cultural tribes, each with its own norms, entertainment and assumptions about the basic facts of the world. And while many people find that scary, it shouldn't be. The rising demographic is the one with a better morality and a better sense of objective reality.

What is more disconcerting is that presidential politics increasingly plays out in only a handful of states that don't truly reflect the national experience. It's long past time to fix that.